Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-speed data transfer to an existing cable television (CATV) system. DOCSIS may be employed to provide Internet access over existing hybrid fiber-coaxial (HFC) infrastructure.
HFC is a telecommunications industry term for a broadband network that combines optical fiber and coaxial cable. It has been commonly employed globally by cable television operators since the early 1990s. The fiber optic network extends from the cable operators' master headend, sometimes to regional headends, and out to a neighborhood's hubsite, and finally to a coaxial cable node that serves anywhere from 25 to 2000 homes. A master headend will usually have satellite dishes for reception of distant video signals as well as Internet protocol (IP) aggregation routers. Some master headends also house telephony equipment for providing telecommunications services to the community.